The present invention relates to a new and improved construction of apparatus for the compensation of masses, also referred to herein as mass compensation, at machines driven by means of a crank drive, especially punch presses or stamping machines.
Generally speaking, the aforementioned mass compensation apparatus is of the type comprising at least one compensation weight which is connected through the agency of a rod mounted at the machine housing with a piston or crosshead and the crank drive in order to realize mass compensation of both the oscillating masses and the rotating masses. A double-lever of the rod is hingedly connected by means of its one end with the compensation weight for realizing mass compensation of the rotating masses and with its other end is hingedly connected via a first guide or link with the crank drive.
According to a prior art apparatus of this type as taught, for instance, in Swiss Pat. No. 427,442, the one end of the double-lever of the rod is connected via a guide or link with the associated compensation weight for producing the mass compensation of the rotating masses. The intermediate bearing of the double-lever is directly supported in the machine housing.
With this arrangement during adjustment of the stroke of the crank drive there thus results an error in the extreme positions during the movement of the compensation weight for compensating the rotating masses. The mass compensation is thus no longer accurate.